[Tagging] maxspeed:type vs source:maxspeed // StreetComplete

Greg Troxel gdt at lexort.com
Wed Sep 19 12:08:18 UTC 2018

Tod Fitch <tod at fitchdesign.com> writes:

>> On Sep 18, 2018, at 6:19 PM, Joseph Eisenberg <joseph.eisenberg at gmail.com> wrote:
>> So on the boundary=administrative admin_level=6 for Rogers County, we could have something like maxspeed:type:default=45mph
> Except that more typically there will be different default speed
> limits on each of the various OSM highway classifications. So maybe
> something more like “maxspeed:default:residential=25 mph”.

I am not aware of *unposted* default limits in the US being different by
an entity smaller than state.   In Massachusetts, there are default
limits in state statutes, in particularly 30 mph in "thickly settled"
areas (also defined in statute).  Some towns have adopted 25 mph in
thickly settled areas, and they have signs at the town borders.

It's an interesting question at what level to tag individual roads and
when to have some way of expressing rules and therefore to expect all
data consumers to evaluate the rules.  My quick reaction is that
publishing rules for regions smaller than states is going to be too
messy, vs just tagging the ways.

With respect to maxspeed:default:residential, that's totally unworkable
in Massachusetts.  The law does not talk about roads or even define them
as residential or not.   The question for 30 (vs 40) is whether the road
is "thickly settled", which is

  built up with structures devoted to business, or the territory
  contiguous to any way where the dwelling houses are situated at such
  distances as will average less than two hundred feet between them for
  a distance of a quarter of a mile or over.

So there are many roads that are properly tagged "residential" but are
not subject to the lower speed.

In Mass, we have speed limit tags on almost all legal roads.  To me,
that seems like the most straightforward approach, even if there are
also defaults.

If the general defaults are intended for routing, that seems more or
less ok.  If they are intended to actually provide speed limit guidance
to drivers, I'm opposed, at least in jurisdictions where they aren't
strictly reliable.

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